1. Field of the Invention
This invention relates to a suspension system for front wheels of a low-body bus such as a long-distance bus or a city bus and, more particularly to a suspension system which can lower floor height and widen a width of the vehicle floor.
2. Description of the Prior Art
Since the function of the front wheels is different from that of the rear wheels, the type of suspension system applied to the former is different from the latter.
Generally, a rigid axle type of suspension is applied to front wheels of a commercial vehicle. However, in order to improve ride comfort and steering stability, an independent type of suspension is often applied to a commercial vehicle.
Since a conventional independent type of suspension has a vertical shock absorber to absorb impacts or vibrations from the front wheels, there is a limit to the floor height.
FIG. 3 shows a conventional independent type of suspension system for a commercial vehicle, which includes a pair of air springs 52 for supporting a vehicle body 50, a pair of supports 54 for supporting the air springs 52 respectively, a wheel carrier 58 rotatably mounted on a wheel for connecting the wheel 60 to the support 54, a pair of shock absorbers 62 connected to the inside of each support 54, a pair of upper arms 66 for connecting an upper portion of each of the supports 54 to a side frame 68, and a pair of lower arms 56 connected to a center frame 70.
In these kinds of suspension systems, when impact and the vibration occurs, the front wheel 60 vibrates about hinge points P1 and P2, a connection point of the side frame 68 and the upper arm 66 and that of the center frame 70 and the lower arm 56, respectively. At this time, the air springs 52 and the shock absorbers 62 dampen the impact and reduce the vibration.
However, since this kind of suspension includes the vertical support 54, an air spring 52 on the support 54, and a vertical shock absorber 62, a floor 64 on these suspension elements are disposed high from the ground.
Further, since the floor 64 is disposed inside the air springs 52, the width of the floor 64 is limited.
The floor 64 is preferred to be disposed at a low position close to the ground and to be wide for the sake of convenience.